Retirement Benefits

9 Months Ended

Sep. 30, 2023

Retirement Benefits [Abstract]

Retirement Benefits

RETIREMENT BENEFITS

The Southern Company system has a qualified defined benefit, trusteed, pension plan covering substantially all employees, with the exception of employees at PowerSecure. The qualified pension plan is funded in accordance with requirements of the Employee Retirement Income Security Act of 1974, as amended (ERISA). No mandatory contributions to the qualified pension plan are anticipated for the year ending December 31, 2023. The Southern Company system also provides certain non-qualified defined benefits for a select group of management and highly compensated employees, which are funded on a cash basis. In addition, the Southern Company system provides certain medical care and life insurance benefits for retired employees through other postretirement benefit plans. The traditional electric operating companies fund other postretirement trusts to the extent required by their respective regulatory commissions. Southern Company Gas has a separate unfunded supplemental retirement health care plan that provides medical care and life insurance benefits to employees of discontinued businesses.

See Note 11 to the financial statements in Item 8 of the Form 10-K for additional information.

On each Registrant's condensed statements of income, the service cost component of net periodic benefit costs is included in other operations and maintenance expenses and all other components of net periodic benefit costs are included in other income (expense), net. Components of the net periodic benefit costs for the three and nine months ended September 30, 2023 and 2022 are presented in the following tables.

	Southern Company		Alabama Power		Georgia Power		Mississippi Power		Southern Power		Southern Company Gas
	(in millions)
Three Months Ended September 30, 2023
Pension Plans
Service cost	$	69	$	16	$	17	$	2	$	2	$	6
Interest cost	156		37		48		7		2		11
Expected return on plan assets	(307)		(75)		(97)		(13)		(4)		(22)
Amortization:
Prior service costs	—		—		—		—		—		(1)
Regulatory asset	—		—		—		—		—		4
Net (gain) loss	8		2		4		1		—		(1)
Net periodic pension income	$	(74)	$	(20)	$	(28)	$	(3)	$	—	$	(3)
Postretirement Benefits
Service cost	$	4	$	1	$	1	$	—	$	—	$	—
Interest cost	18		5		6		1		—		2
Expected return on plan assets	(21)		(9)		(7)		(1)		—		(2)
Amortization:
Prior service costs	—		—		1		—		—		—
Regulatory asset	—		—		—		—		—		2
Net gain	(4)		(1)		(1)		—		—		(1)
Net periodic postretirement benefit cost (income)	$	(3)	$	(4)	$	—	$	—	$	—	$	1
Nine Months Ended September 30, 2023
Pension Plans
Service cost	$	207	$	48	$	51	$	8	$	5	$	18
Interest cost	469		109		143		21		6		32
Expected return on plan assets	(922)		(223)		(289)		(41)		(12)		(65)
Amortization:
Prior service costs	—		—		1		—		—		(2)
Regulatory asset	—		—		—		—		—		11
Net (gain) loss	24		7		10		1		—		(3)
Net periodic pension income	$	(222)	$	(59)	$	(84)	$	(11)	$	(1)	$	(9)
Postretirement Benefits
Service cost	$	11	$	3	$	3	$	—	$	—	$	1
Interest cost	53		13		19		2		—		6
Expected return on plan assets	(62)		(26)		(22)		(1)		—		(5)
Amortization:
Prior service costs	1		—		1		—		—		—
Regulatory asset	—		—		—		—		—		5
Net gain	(10)		(2)		(3)		—		—		(3)
Net periodic postretirement benefit cost (income)	$	(7)	$	(12)	$	(2)	$	1	$	—	$	4

	Southern Company		Alabama Power		Georgia Power		Mississippi Power		Southern Power		Southern Company Gas
	(in millions)
Three Months Ended September 30, 2022
Pension Plans
Service cost	$	103	$	25	$	26	$	5	$	2	$	9
Interest cost	102		24		31		5		2		7
Expected return on plan assets	(316)		(77)		(99)		(15)		(4)		(22)
Amortization:
Prior service costs	—		—		—		—		—		(1)
Regulatory asset	—		—		—		—		—		3
Net loss	60		16		18		2		1		2
Net periodic pension cost (income)	$	(51)	$	(12)	$	(24)	$	(3)	$	1	$	(2)
Postretirement Benefits
Service cost	$	6	$	2	$	2	$	1	$	1	$	—
Interest cost	10		3		4		—		—		1
Expected return on plan assets	(20)		(9)		(8)		—		—		(2)
Amortization:
Prior service costs	(1)		—		—		—		—		—
Regulatory asset	—		—		—		—		—		2
Net (gain)/loss	1		—		—		—		—		(1)
Net periodic postretirement benefit cost (income)	$	(4)	$	(4)	$	(2)	$	1	$	1	$	—
Nine Months Ended September 30, 2022
Pension Plans
Service cost	$	309	$	74	$	78	$	13	$	7	$	26
Interest cost	306		72		92		14		5		21
Expected return on plan assets	(949)		(229)		(298)		(44)		(12)		(68)
Amortization:
Prior service costs	—		—		1		—		—		(2)
Regulatory asset	—		—		—		—		—		11
Net loss	180		47		55		9		2		5
Net periodic pension cost (income)	$	(154)	$	(36)	$	(72)	$	(8)	$	2	$	(7)
Postretirement Benefits
Service cost	$	17	$	5	$	5	$	1	$	1	$	1
Interest cost	31		8		11		1		—		4
Expected return on plan assets	(60)		(25)		(21)		(1)		—		(6)
Amortization:
Prior service costs	(1)		—		—		—		—		—
Regulatory asset	—		—		—		—		—		5
Net (gain) loss	1		—		1		—		—		(2)
Net periodic postretirement benefit cost (income)	$	(12)	$	(12)	$	(4)	$	1	$	1	$	2